In recent years, wing-flapping flying apparatuses have been developed, which are capable of flying by mechanically performing upward-and-downward movements of the wings similar to a bird's flap of wings. Such wing-flapping flying apparatuses were configured to convert rotatary motion from a power source into reciprocating motion, thereby moving its wings upward and downward by means of appropriate mechanisms.
One example of prior art wing-flapping flying apparatuses is disclosed in Korean Utility-Model Registration Publication No. 20-0117142 (Hong). This publication discloses a bird-shaped flying toy, wherein twisted elastic strings are used as a power source and wing frames secured to lateral opposed sides of a hollow body are moved up and down. Also, Korean Utility-Model Registration Publication No. 20-0336766 (Chang) discloses a drive mechanism of a wing-flapping flying object, wherein the rotation of an electric motor is appropriately adjusted by means of a transmission and wings are caused to be moved up and down around hinges provided on a body portion by means of a crank mechanism. Also, Korean Patent Registration Publication No. 10-0450535 (Yoon, et al.) discloses a compressed air engine and a flying toy using the same, wherein wings are caused to be moved upward and downward by using a compressed air.
These prior art wing-flapping flying apparatuses employed a mechanism capable of converting rotatary motion generated from a power source using a human power or an electrical power into reciprocating motion or directly generating reciprocating motion so as to effectuate their flights by simply flapping the wings upward and downward. However, the simple upward-and-downward movements of the wings generate lift only when the wings are downwardly moved and offset the generated lift when the wings are upwardly moved. Thus, there is a problem in that the lift required for the flight of the flying object is not generated throughout an entire wing-flapping movement.
Further, there is another problem in that the size and weight of the flying object respectively become larger and heavier. This is because the wings need to be bigger in order to complement the lack of lift and the mechanism for converting the rotatary motion from the power source into the reciprocating motion need to be provided.
Moreover, since the simple upward-and-downward movements of the wings in the prior art wing-flapping flying apparatuses merely act to ensure that the flying apparatus does not fall down when staying in the air, there is yet another problem in that the upward, downward and forward flights cannot be easily effectuated.